One of the most striking characteristics of speech production is its variability. The list of variables that can influence the extent and degree of articulatory variation is extensive, ranging from active control processes to noise in neural signals and constraints due to the anatomy and biomechanics of the speech production mechanism. Our aim in this research is to be able to separate these sources of variation and in so doing to isolate the characteristics of control signals in speech production from other determinants of speech behaviors. We focus on a number of fundamental issues in speech motor control: the relative roles of neural and biomechanical factors in coordination and coarticulation, the effects of biophysical (non-linguistic) variables on speech movements, and the development of an integrated model of the biomechanics and neural control of the orofacial articulators. The work proposed in this application is focused on developing an understanding of the basic sensorimotor processes and organizing principles of speech production. A fundamental goal of this work is to develop a neural control model of speech production. This is a substantial effort requiring contributions from groups and individuals with overlapping interests and complementary expertise in the areas of physiology, statistics, robotics, computer science, linguistics, and motor control. This renewal represents an expansion of the scope of the previous application through the inclusion of new collaborators, all of whom have worked with us during this past grant period. The group represents an integration of prominent researchers and highly skilled younger scientists with a common focus --- providing a theoretical and empirical framework for understanding speech production. This effort is multidisciplinary and has the potential for significant clinical relevance by providing a biological foundation for interpreting normal and disordered speech and language processes.